Evaporation Modeling for Sub-surface Reservoirs

Abstract

Evaporation losses are the major problem effects on small dam's reservoirs in water harvesting systems. In this paper, evaporation modeling for sub-surface reservoirs was developed. The physical model contains four squares cross section tanks of (91.4) cm length and (46.2) cm depth (Colorado Sunken Pan). Three tanks were filled with different types of earth fill materials while the forth one filled with water. New instrument was developed to measure the amount of evaporation losses from gravel and sand, then comparing with free surface evaporation losses in order to estimate the amount of water that can be saved by using these types of small dams. The field study was achieved with the model during the period (Dec 2010-Feb 2012). The evaporation losses was reduced about 60 % when the water table below gravel surface by 10 cm only, while at 20 cm depth of the water table the evaporation reduction was about (85 % to 89%) from cores gravel and fine gravel respectively .